1. Field of the Invention
The present invention relates generally to computer systems and peripherals. More specifically, the present invention is an eye-tracking system and method for determining the direction of a user""s gaze, positioning a display pointer at a point of regard, and for controlling a computer by employing the movement of the user""s eyes.
2. Description of the Related Art
Eye controlled devices have been used to control the operation of a computer, and more specifically, have used a sensor to track the position of the center of the eye as the eye gazes upon a point of regard, to position a pointer on a video screen.
U.S. Pat. No. 5,345,281, issued to Taboada et al. in 1994 discloses a device for computer cursor positioning by tracking the gaze of the human eye by the analysis of the reflection off the eye of an infrared beam, and requires manual activation of controls. U.S. Pat. No. 5,367,315, issued to Pan in 1994, discloses an eye-controlled device with manual or foot activation. These devices are neither well suited for users requiring a hands-free environment, nor are these devices well suited for those users who are physically challenged.
Another user mounted device is disclosed in U.S. Pat. No. 5,481,622, issued to Gerhardt et al. in 1996, and discloses a helmet mounted camera, video screen, a computer connected to a frame grabber which in turn is connected to the camera, and a computer program for calibrating the position of the user""s eye to the video screen and for providing feedback to the user in the form of a cursor on the display screen at a position determined by the gaze of the user. The Gerhardt system determines the center of the user""s eye by binary segmentation of the digitized image determined by setting thresholds for the properties of the pixel image. This method of encoding threshold levels for digitized video signals is further disclosed in U.S. Pat. No. 4,648,052, issued to Friedman et al. in 1987, for an eye tracker communication system. Still another head mounted eye sensing unit is disclosed by Eberi, et al. in U.S. patent application Ser. No. 2002/0101568, which includes a signal input unit, a wireless communications unit, and an output unit.
While in some situations a user mounted camera may be seen as an encumbrance, remote mounted tracking devices are ill-suited when the user is actively moving their head or body independent of gazing at a point of regard. U.S. Pat. Nos. 4,836,670; 4,950,069; and 4,973,149 issued to Hutchinson disclose eye mouse devices remote from the user that not only control the movement of a cursor on a computer screen or display by the movement of the user""s eyes, but furthermore, the activation or selection is accomplished by the user dwelling, gazing, or staring at a desired activation region for a pre-determined amount of time. Further examples of this type of device are seen in U.S. Pat. No. 5,850,211, issued to Tognazzini in 1998, which discloses a eye track driven scrolling device mounted to the top of a video terminal and U.S. Pat. No. 6,215,471, issued to DeLuca in 2001, which discloses a computer pointer controlled by a camera mounted on a display terminal aimed at the user""s face, further disclosing selection of controls by the closure of one or both of the user""s eyes.
An attempt to correct this limitation is disclosed by Lemelson et al. in U.S. patent application Publication Ser. No. 2002/0105482 in which a gimbaled sensor system incorporates servo mechanisms mounted on a fixed display terminal to track the user""s head and eye movements. Mechanical devices, however, are by themselves a limitation and are not suitable for all applications.
Other eye-tracking devices use an eye sensor focused on the eye of the user to view the image created by the reflected light on the retina to determine the direction of user gaze. Such a device is disclosed in U.S. Pat. No. 6,394,602, issued to Morrison et al. in 2002.
Another point of gaze tracker is U.S. Pat. No. 5,471,542, issued to Ragland in 1995, and discloses a video camera aimed at the user""s eye to analyze the digital image formed by the iridal ellipse, the points being on the boundary between the eye""s sclera and the iris as represented by different light intensities.
An additional eye tracking system was disclosed in U.S. Pat. No. 5,331,149, issued to Spitzer et al. in 1994, and refers to a system using a photo detector array to detect light reflecting from a user""s eye.
Another image pickup apparatus was disclosed in U.S. Pat. No. 6,388,707, issued to Suda in 2001, and refers to a system capable of range finding comprising infrared light sources and charge coupled detectors.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a computer-pointing device actuated by eye movement solving the aforementioned problems is desired.
The invention is an eye-tracking system which determines the point of regard of the user""s gaze based upon the position of a user""s eye relative to a position on a display screen, comprising a camera for acquiring a video image of the eye; a support for the camera; an eye tracking interface connected to the camera for accepting and converting analog video data from the camera and converting the analog data to digital pixel data; a computer coupled to the interface for processing the digital data from the camera; and specialized computer software which determines the position of the user""s gaze depending upon an analysis of the pixel intensity of the digitized image. (The camera, of course, could be using monochrome or color film, or it could be a digital camera.) The computer provides feedback to the user in the form of a pointer positioned on the display screen positioned at the point of the user""s gaze and provides the user with the capability to perform computer actions based upon the length of time the user locks his view on the point of regard. The system may include additional sensors mounted proximate to the camera for determining the axial position of the camera, thereby compensating for perceived eye movement when in fact, the point of regard has not changed. The user mounted sensors, eye tracking interface and computer may communicate by wire or by wireless means.
Accordingly, it is a principal object of the invention to provide a system for tracking the movement of a user""s eye and correlate its position relative to a specific location on a video screen that includes: a camera focused on the eye of a user, a CPU, a memory, a video screen, an eye tracking interface, a computer readable program code means stored in the memory, and a means for reading the computer readable program code into the memory either from another computer or from a computer useable medium having computer readable program code means embodied thereon.
It is another object of the invention to provide a method for compensating for unintentional movement of the video screen, the camera or both, relative to the user""s eye, after calibration of the system.
It is a further object of the invention to provide an eye-tracking computer pointing device that can replace or supplement a conventional handheld computer mouse.
Still another object of the invention is to provide an alternative to a xe2x80x9cjoy stickxe2x80x9d for video game industry.
An additional object of the invention is to provide a virtual keyboard as a replacement for a standard computer keyboard.
It is another object of the invention to provide a usable interface for handicapped persons to control any computer-controlled device having a video screen and a communication port.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.